Back Orifice 2000

Back Orifice 2000 (often shortened to BO2k) is a computer program designed for remote system administration. It enables a user to control a computer running the Microsoft Windows operating system from a remote location. The name is a pun on Microsoft BackOffice Server software.

BO2k debuted on July 10, 1999 at DEF CON 7 computer security convention in Las Vegas, Nevada. It was originally written by Dildog, a member of US hacker group Cult of the Dead Cow. It was a successor to the cDc's Back Orifice remote administration tool, released the previous year. As of 2007, BO2k is being actively developed.

Whereas the original Back Orifice was limited to the Windows 95 and Windows 98 operating systems, BO2k also supports Windows NT, Windows 2000 and Windows XP. Some BO2k client functionality has also been implemented for Linux-systems. In addition, BO2k was released as free software, which allows one to port it to other operating systems.